Collaborative Research: Modeling-Based Design of Freeze-Cast Hybrid Materials

冷冻铸造工艺是一种可以很容易地制造几立方厘米大小的大块材料和整个部件的工艺。该工艺是基于水基溶液或浆液（悬浮液）的凝固。冻铸支架时，将溶液或浆液倒入模具中，然后定向凝固。在冷冻过程中，水以纯冰晶的形式凝固，溶解的聚合物和悬浮在这种液体载体中的颗粒被集中在它们之间。冷冻后，将样品冷冻干燥，使冰相升华，露出材料支架；它的结构是作为模板的冰晶的反面。细胞壁材料结构是自组装过程的结果。冷冻铸造或“冰模板”是一种相对便宜的方法，提供了一种模拟复杂、高效的天然材料的方法，在几个长度尺度上进行分层设计。该奖项支持建立模型、基本设计原则和工具的研究，这将使设计和制造具有增强性能的冻铸混合材料的系统方法成为可能。这些新材料的应用范围从能量产生和储存到组织修复和再生，对个人和公众都有好处。本研究项目侧重于基础科学和模型驱动的冻铸混合材料设计。一个在建模、实验和表征方面具有专业知识的跨学科团队将解决当前的知识空白，并分析由冷冻铸造过程产生的冰相和冰模板材料结构的形成和演变，试图揭示基本的物理化学原理，并确定基本的加工-结构-性能相关性。三个研究目标是：(1)确定潜在的基础材料科学，并建立一个在明确定义的衬底（石墨烯）上冷冻铸造过程中冰晶成核和生长的现实模型；(2)将多尺度计算模型与实验方法相结合，揭示加工-结构-属性的相关性；(3)建立预测模型，以确定最有前途的加工-添加剂组合，以便在模型材料系统中定制设计和优化结构形成和性能。

The freeze-casting process is one with which bulk materials and entire components of several cubic centimeters in size can be manufactured with ease. The process is based on the solidification of water-based solutions or slurries (suspensions). To freeze-cast a scaffold, a solution or slurry is poured into a mold and then directionally solidified. During freezing, the water solidifies in the form of pure ice crystals, and the polymer that was dissolved and the particles that were suspended in this liquid carrier are concentrated between them. Once frozen, the sample is freeze-dried to sublime the ice-phase and reveal the material scaffold; its architecture is the negative of the ice crystals which templated it. The cell wall material structure is the result of a self-assembly process. Freeze casting or "ice templating" is a relatively inexpensive procedure and provides a means to mimic complex, efficient natural materials with hierarchical designs over several length-scales. This award supports research to build models, basic design principles and tools that will enable a systematic approach for the design and manufacture of freeze-cast hybrid materials with enhanced performance. These new materials will be of benefit to both individuals and the general public at large through applications that range from energy generation and storage to tissue repair and regeneration.This research program focuses on the fundamental science and modeling-driven design of freeze-cast hybrid materials. An interdisciplinary team with expertise in modeling, experiment and characterization will address current knowledge gaps and analyze the formation and evolution of the ice phase and ice-templated material architectures generated by the freeze casting process in an attempt to uncover basic physicochemical principles and determine fundamental processing-structure-property correlations. The three research goals are to (1) determine the underlying fundamental materials science and establish a realistic model for ice-crystal nucleation and growth on a well-defined substrate (graphene) during freeze casting; (2) uncover processing-structure-property correlations by combining multiscale computational modeling with experimental approaches; and (3) develop predictive models to identify the most promising processing-additive combinations in order to custom-design and optimize structure formation and performance in the model material system.